Plasticizer Free Curing Composition

ABSTRACT

Plasticizer free curing compositions comprising small particle size complexes of methylenedianiline and an alkali salt, e.g. a 3:1 coordination complex of MDA/alkali salt, with average diameter 60 micron or less, often 20 micron or less, e.g., 10 microns or less, dispersed in a volatile, non-polar, organic solvent are prepared. Stable one pack urethane compositions comprising the plasticizer free curing compositions and polyurethane prepolymers are prepared, which exhibit excellent storage stability and overcome many of the drawbacks encountered when using MDA complexes dispersed in plasticizers such as high boiling aromatic and alkyl di-esters.

This application claims benefit under 35 USC 119(e) of U.S. ProvisionalApplication No. 61/881,615 filed Sep. 24, 2013, the disclosure of whichis incorporated herein by reference.

The invention provides a curing composition comprising small particlesof a methylenedianiline/alkali metal salt coordination complex, anon-polar organic solvent with a bp of 160° C. or less, and less than 1wt % of a plasticizer; a method for preparing the curing composition;and a polyurethane composition comprising an isocyanate terminatedprepolymer and the small particle methylenedianiline/alkali metal saltcoordination complex of the curing composition.

BACKGROUND OF THE INVENTION

It has long been known that certain complexes of aromatic di-amines, forexample, alkali metal salt complexes of 4,4′-methylenedianiline (MDA),can be used to cure amine-curable polymers or prepolymers withoutpremature reaction between the curable polymer or prepolymer and theaforementioned diamines. These amine complex curatives have found use inso called one-pack polyurethanes, i.e., urethane compositions containingisocyanate terminated prepolymers, formed by reacting a polyol andpoly-isocyanate, and curative which are designed to not react untilactivated, typically by heating.

Commercially available curing compositions comprising coordinationcomplexes of aromatic diamines and metal salts are formulated asdispersions in high boiling liquids, typically liquids widely known asplasticizers, such as phthalate diesters.

U.S. Pat. No. 3,876,604 discloses a dispersion of a coordination complexof MDA and an alkali metal salt in an inert liquid vehicle. The MDAcomplex is formed by reacting an aqueous solution or brine containing asodium or lithium chloride, bromide, iodide or nitrite salt with amethanolic solution of MDA. The MDA coordination complex has a 3:1 moleratio of MDA to alkali metal salt and is isolated as a crystallineprecipitate e.g., by filtration, decantation, centrifuging or othersuitable operation, with a particle size of ≧150 microns.

In order to be effective as a curing agent, e.g., a curing agent for apolyurethane prepolymer, the particle size of the complex needs to beless than 60 microns. The particle size of the MDA complex produced bythe process of U.S. Pat. No. 3,876,604 is too large to be effective,i.e., ≧150, and so a grinding or milling step is required to produceeffective material.

It was found however that relatively intensive mixing is required toadequately disperse the finely divided curing agent when added alone toa polymer or prepolymer, e.g., a polyurethane prepolymer. This is notjust inconvenient but may result in some premature curing because of theheat generated from the mixing operation. A major advantage of using adispersion of the MDA complex in an inert liquid vehicle is that thecuring agent can be uniformly dispersed throughout the prepolymer orpolymer without expending excess energy or generating the heat thatwould cause premature cure.

The inert liquid vehicle must be inert to both the complex and polymeror prepolymer being cured, be readily miscible with the prepolymer orpolymer which is to be cured so that the liquid and polymer may bereadily comingled, and in general must possess sufficiently lowvolatility so as not to vaporize from the cured polymer after curing orduring end-use applications. One exception to the low volatilityrequirement is in applications where the loss of a solvent-like materialcould take place without difficulty such as in surface coatings and ifthe liquid vehicle is sufficiently low boiling, such as methylenechloride, it can serve as an expanding agent during the curing operationto yield cellular products.

The importance of the mutual compatibility of the liquid phase of thecuring agent dispersion and the polymer or prepolymer being cured isillustrated by the following example. Nujol oil, a saturated lighthydrocarbon petroleum oil, readily forms a stable dispersion with thecomplex; however, the resultant mixture is incompatible with polyetherpolyurethanes, among other polymers and prepolymers, and thus Nujoldispersions are considered ineffective for curing such prepolymers.

Examples of suitable liquid carriers found in the art include esters ofphthalic acid, isophthalic acid, trimellitic acid aliphatic diacids suchas adipic, azeleic and sebacic acids, aromatic and naphthenichydrocarbon processing oils, halogenated biphenyls and liquid aromaticsulfonamides. Specific examples include di(2-ethylhexyl)phthalate,tetraethylene glycol bis(2-ethylhexanoate), and an aromatic process oilcomprising 18% polar compounds, 76% aromatics and 6% saturated petroleumderivatives. Paraffinic hydrocarbon oils have limited compatibility withmost of the well-known amine-curable polymers and therefore areconsidered to be of value only on rare occasion.

U.S. Pat. No. 3,899,438 discloses that a dispersion of small particlesof a MDA/alkali metal salt coordination complex can be formed in asuitable inert liquid carrier in a one step process, i.e., without aseparate milling step, by running the reaction in a high shear mixer,such as a ball mill or high speed disperser run at 7,000 rpm. Suitableinert carrier liquids include di(2-ethylhexyl) phthalate andtetraethylene glycol bis(2-ethylhexanoate). U.S. Pat. Nos. 4,282,344 and4,075,150 disclose a process similar to that of U.S. Pat. No. 3,899,438wherein excess MDA is removed by reaction with added isocyanate (U.S.Pat. No. 4,282,344) or an aromatic mono-carbodiimide (U.S. Pat. No.4,075,150). A similar process is also disclosed in U.S. application Ser.No. 12/754,944, now U.S. Pat. No. 8,586,682.

Commercially available curing compositions comprising coordinationcomplexes of aromatic diamines and metal salts are formulated asdispersions in high boiling liquids, typically liquids widely known asplasticizers, i.e., aromatic diesters such as dioctyl phthalate, andalkyl diesters such as dioctyl adipate. When the curing composition isadded to a prepolymer and the mixture is heated and cured, theplasticizer remains in the product. Plasticizers have negative effectson polyurethane polymers such as reduced dynamic and mechanicalproperties and environmental, health and safety issues due to thepartial volatilization of plasticizer (smoke formation) during cure havebeen encountered. There is therefore a need for a readily prepared andhighly effective curative composition for amine curable polymers thatavoids the use of the current plasticizer carrier liquids and theproblems caused by them.

SUMMARY OF THE INVENTION

Curing compositions comprising a small particle size MDA/alkali saltcoordination complex, i.e., average diameter 60 micron or less, often 20micron or less, e.g., 10 microns or less, dispersed in a volatile,non-polar, organic solvent, which are essentially free of ester basedplasticizers and high boiling hydrocarbon carriers, are provided. Thecuring compositions of the invention are surprisingly highly effectivein preparing storage stable one pack urethane compositions, overcomemany of the drawbacks of the present commercially available dispersionsof MDA complexes in high boiling aromatic and alkyl di-esters, and arereadily prepared in good yield and high purity.

DESCRIPTION OF THE INVENTION

Provided is a curing composition, in particular a composition for curingamine curable polymers such as polyurethanes made from isocyanateterminated prepolymers, epoxy resins and the like, comprising:

-   -   an inert liquid carrier having a polarity index of less than        about 3.7 and a boiling point at atmospheric pressure of 160° C.        or less; and    -   a 3:1 coordination complex of 4,4′-methylenedianiline and an        alkali metal salt formed as solid particles having an average        diameter of from 0.1 to 50 μm, wherein the curing composition        comprises less than 1 wt %, for example less than 0.1 wt % or        less than 0.01 wt %, of a plasticizer selected from the group        consisting of esters of polycarboxylic acids and monohydric        alcohols or phenols, esters of polyols and monocarboxylic acids,        triesters of phosphoric acid, aromatic hydrocarbons with a        boiling point of over 200° C. and aliphatic hydrocarbons with a        boiling point of over 200° C.

The relative concentrations of the inert carrier and coordinationcomplex in the composition may vary, for example in one broad embodimentthe curing composition comprises

-   -   from 10 to 90 wt % of the coordination complex and    -   from 10 to 90 wt % of the inert liquid carrier    -   based on the total weight of the combination of coordination        complex and carrier:        for example,    -   from 20 to 80 wt %, e.g. 30 to 70 wt %, or 40 to 60 wt % of the        coordination complex and    -   from 20 to 80 wt % e.g. 30 to 70 wt %, or 40 to 60 wt % of the        inert liquid carrier based on the total weight of the        combination of coordination complex and carrier.

The curing composition will often comprise other optional components,such as surfactants, additives, reaction byproducts etc., in addition tothe MDA coordination complex and inert liquid carrier. For example, insome embodiments the composition comprises:

-   -   from 10 to 90 wt % of the coordination complex,    -   from 10 to 90 wt % of the inert liquid carrier and    -   from 0 to 20 wt % other components,    -   based on the total weight of the curing composition:        for example:    -   from 30 to 70 wt % of the coordination complex,    -   from 10 to 70 wt % of the inert liquid carrier and    -   from 0 to 20 wt %, e.g., from 0 to 10 wt %, or from 0 to 5 wt %        other components, based on the total weight of the curing        composition.

In many embodiments the composition will comprise at least 0.1 wt %, 0.5wt %, 1 wt %, or 2 wt %, but less than 20 wt %, 15 wt %, 10 wt %, or 7wt % of components such as surfactants, additives, reaction byproductsetc. The components other than coordination complex and carrier will bediscussed in more detail later in this disclosure.

For example, in some embodiments the composition comprises:

-   -   from 20 to 80 wt % of the coordination complex,    -   from 19 to 79 wt % of the inert liquid carrier and    -   from 1 to 20 wt % other components based on the total weight of        the curing composition:        for example:    -   from 30 to 70 wt % of the coordination complex,    -   from 29 to 69 wt % of the inert liquid carrier and    -   from 1 to 20 wt %, e.g., from 1 to 10 wt %, or from 1 to 5 wt %        of other components based on the total weight of the curing        composition.

The curing composition comprises a coordination complex of 4,4′-MDA anda salt, also referred to herein as a “4,4′-MDA complex” or “MDAcomplex”. The alkali metal salt of the complex is typically a compoundMX wherein M is typically Li, Na or K and X is an anion. Typically X isa halide anion such as Cl, Br or I, most often Cl or Br. Thestoichiometry of the coordination complex is known in the art to be 3:1ratio of MDA to alkali metal salt.

The 4,4′-MDA complex may be present in the curing composition in anamount ranging from 10 wt % to 90 wt % based on the total weight of thecuring composition, typically the 4,4′-MDA complex is at least 15 wt %,20 wt % or 25 wt % of the curing composition. Generally the compositioncomprises from 30 to 70 wt % or from 40 to 65 wt % of the coordinationcomplex.

The MDA complex is produced as particles having an average diameter offrom 1 to 50 μm, often 20 micron or less, e.g., from 5 to 35 μm or from10 to 15 μm. Generally 90% by weight or more of all coordination complexparticles in the curing composition have a diameter of 50 microns orless. In some embodiments, at least 90% of the particles have andiameter of less than 45 μm, e.g., less than 30 μm, and often 20 micronsor less. In particular embodiments at least 95% less than 10 microns indiameter, e.g., 95% having a maximum diameter of 5 microns and or about99% having a maximum diameter of 5 microns. The average particle sizesof MDA complex particles can be determined, for example, by means of aphotomicrograph in a known manner.

The inert liquid carrier of the invention is an organic solvent having apolarity index of less than about 3.7 and a boiling point at atmosphericpressure of 160° C. or less.

It has quite surprisingly been found that non-polar solvents such asalkanes, cylclo-alkanes, and alkyl substituted benzenes, not only serveas a medium in which the MDA complex having a small particle size isprepared, but are also very effective in aiding the dispersion of MDAcomplex particles throughout curable substrates, for example,polyurethane prepolymers. This is in contrast to the teachings of theart wherein similar non-polar carriers such as nujol are taught to beincompatible with, e.g., polyether polyurethanes, and their use incuring compositions for such polymers is said to be ineffective. Forexample, carriers with a polarity index of from 0 to about 3.5 or from 0to about 3.1 have been found to be effective. Often the carrier of theinvention will have a polarity index of from 0 to about 3.0, such asfrom 0 to 2.7, and carriers with a polarity index of 2.5 or less, suchas toluene, and carriers with a polarity index of less than 2.0, lessthan 1.5 such as methyl cyclohexane, less than 1.0 and even less than0.5, such as cyclohexane, have provided excellent results.

One advantage in using volatile solvents as carriers in the presentcuring compositions is that once the curing composition is added anddispersed in the polymer or prepolymer to be cured it can be removed bydistillation, typically at low pressure, before cure and withoutinitiating premature curing. In many embodiments the carrier has a bp atatmospheric pressure of less than 150° C. For example, the carrier has abp from about 40° C. to about 145° C., from 45° C. to about 140° C., orfrom about 50° C. to about 140° C. In one particular embodiment thecarrier has a bp from about 60° C. to about 120° C.

For example, the inert liquid carrier is selected from the groupconsisting of

-   -   C₅₋₉ straight or branched alkyl or alkene;    -   C₂₋₆ straight or branched alkyl or alkene substituted by one or        more halogen;    -   C₄₋₈ straight or branched alkyl interrupted by oxygen;    -   C₅₋₈ cycloalkyl or cycloalkene;    -   C₅₋₈ cycloalkyl or cycloalkene substituted by one or more C₁₋₃        straight chain alkyl, C₃ branched alkyl, F, Cl, or Br; and    -   benzene, and benzene substituted by one or more C₁₋₃ straight        chain alkyl, C₃ branched alkyl, F, Cl or Br.

In some embodiments the inert liquid carrier is selected from the groupconsisting of

-   -   C₆₋₈ straight or branched alky;    -   C₅₋₇ cycloalkyl;    -   C₅₋₇ cycloalkyl substituted by one or more methyl or ethyl        group; and    -   benzene, toluene, o-xylene, m-xylene, p-xylene, and ethyl        benzene.

In some embodiments the carrier is selected from hexane, heptane,octane, branched isomers of hexane, heptane and octane, cyclohexane,methyl cyclohexane, toluene and ethyl benzene, for example, hexane,iso-octane, cyclohexane and methyl cyclohexane.

The carrier can also be a mixture of one or more organic solvents,including for example, as found in commercial petroleum ethers andxylenes etc.

The curing composition may contain a combined total of 0 to 25 wt %,typically 0 to 20 wt % or less, of various components such assurfactants, unreacted MDA isomers or metal salts, reaction by-productsproduced during preparation of the curing composition, e.g., reactionproduct of an isocyanate and an MDA isomer, and common additives, suchas, for example, pigments, fillers, stabilizers, anti-settling agents,and pore-forming agents and the like. It is highly unlikely that any oneof these optional components is present in an amount of 10 wt or more oreven 5 wt % or more. In general, the curing composition will containfrom 0.1 to 20 wt % of a combination of components other than the MDAcomplex and inert carrier, e.g., from 0.1 to 15 wt %, or from 0.1 to 10wt % such as 0.1 to 5 wt %. In certain embodiments the curingcomposition contains from 0.5 to 15 wt %, 0.5 to 10 wt %. Often, 1% ormore by weight, or 2% or more, but less than 20% or 10% by weight of thecomposition will be other than the MDA complex and inert carrier.

Typically, the curing composition comprises one or more surfactants, forexample, in an amount of from 0.1 to 10 wt %, e.g., from 0.5 to 5.0 wt%, based on the total weight of the curing composition. Suitablesurfactants include, but are not limited to anionic, cationic, andnonionic surfactants, such as oil-soluble surfactants, lecithin, andquaternary ammonium compounds. The curing composition may furthercomprise one or more additional additives, such as, for example,pigments, fillers, solvents, stabilizers, anti-settling agents, andpore-forming agents.

The curing composition of the invention may contain up to 20% of free,unreacted MDA, for example, up to 10% or from 0.01 to 5 wt % of free,unreacted MDA, typically as a mixture of MDA isomers. In some instancethe amount of free MDA will be in the range of 1 to 5 wt % or 1 to 3.5wt %; in other instances the amount of free MDA will be in the range of0.01 to 1 wt %. In certain particular embodiments the amount of free MDAin the curing composition is less than 1000 wppm, e.g., less than 800wppm or less than 500 wppm. In terms of ranges the amount of free MDA isfrom 0 wppm to 1000 wppm, e.g., 50 wppm to 950 wppm, 100 wppm to 800wppm, or from 50 to 500 wppm.

The curing composition of the invention is conveniently prepared in amanner analogous to processes of the art, wherein, of course, someprovision is made for the differences introduced to the process by theuse of the relatively non-polar and volatile carriers of the invention.

For example, in one general embodiment the curing composition isprepared by adding 4,4′-methylenedianiline, to a mixture comprising analkali metal salt, one or more inert liquid carrier of the presentinvention, one or more surfactant, and brine or water to form thecoordination complex, and removing water, typically by distillation,from the mixture comprising the coordination complex.

The reaction between the MDA and the alkali salt, e.g. sodium chloride,sodium bromide etc., proceeds readily at ambient conditions. If desiredone may use elevated temperatures, however, temperatures below 80° C.are recommended. The reaction requires agitation sufficient to keepchanging the interface between the salt-water solution and MDA-carriersolution.

The ratio of MDA to alkali salt in the product is 3:1 but one may chooseto use an excess of either component in the reaction. Typically, thereis at least 0.5 part of water for every 100 parts of alkali salt and inmost instance the amount of water present is insufficient to dissolveall the salt until the complex-forming reaction is at least 50%complete. In general, the relative amounts of the components in thereaction can be found in the art, e.g., U.S. Pat. Nos. 3,899,438;3,876,604; 4,075,150; and U.S. application Ser. No. 12/754,944, now U.S.Pat. No. 8,586,682, the disclosures of which are incorporated herein byreference.

Because the inert carrier of the instant invention may have a by similarto that of water it is typically advised to remove the water in a mannerthat allows for the organic distillate to be separated from the aqueousdistillate and returned to the reaction mixture, e.g. dean stark trapmay be used. It is generally wise to use a solvent that will form anazeotrope with the water being removed, e.g., when using a solvent thatboils at temperatures below 100° C. at atmospheric pressure. Thetemperature during distillation should be kept below the temperature atwhich the MDA complex disassociates, and therefore some level of vacuumis typically required.

Most sources of 4,4′-methylenedianiline also contain 2,4- and 2,2-MDAisomers which typically do not form the desired complex. In certainembodiments, processing steps to remove unreacted 4,4′-MDA, along withthe less the desirable MDA isomers, are employed. For example, thecuring composition may be prepared by;

A) adding 4,4′-methylenedianiline to a mixture comprising an alkalimetal salt, one or more inert liquid carrier of the present invention,one or more surfactant, and brine or water to form the coordinationcomplex,B) removing water from the mixture comprising the coordination complexto form a dry stage intermediate,C) adding an isocyanate compound to the dry stage intermediate to reactwith residual methylenedianiline.

Optionally, additional inert carrier and/or surfactant may be addedalong with the isocyanate compound in step C). Additional carrier and/orsurfactant may be also optionally be added in one or more stepssubsequent to addition of the isocyanate compound in step C). In someembodiments no additional carrier and/or surfactant is added after stepC).

The amount of MDA and carrier used will depend on the desiredconcentration of MDA complex in the product composition. The alkalimetal salt is generally selected from the group consisting of sodiumchloride, sodium bromide, sodium iodide, potassium chloride, potassiumbromide, potassium iodide, lithium chloride, lithium bromide and lithiumiodide, typically sodium chloride, sodium bromide, potassium chloride,potassium bromide, lithium chloride and lithium bromide, for examplesodium chloride, sodium bromide, potassium chloride and potassiumbromide. In many embodiments the surfactant is selected from the groupof lecithin and polyoxypropylated quaternary ammonium halides, althoughother surfactants may be used. Generally the total amount of surfactantemployed is from about 0.5% to about 10% by weight based on the totalweight of the reaction components, typically, the surfactant ranges from1 to 5 wt % or 2 to 5 wt %.

When an isocyanate compound is added to the dry stage intermediate itcan be conveniently selected from the group consisting of phenylisocyanate, p-tolyl isocyanate, cyclohexyl isocyanate, butyl isocyanate,tolylene-2,4-diisocyanate, mixtures of tolylene-2,4-diisocyanate withtolylene-2,6-diisocyanate, 4,4′-methylenebis(phenyl isocyanate),2,4,4′-triisocyanato-diphenyl ether, phenylene-1,4-diisocyanate,4,4′-methylenebis(cyclohexyl isocyanate), para-phenylene diisocyanate,1,6-hexane diisocyanate, isophorone diisocyanate, 3,3′-bitoluenediisocyanate, 1,4-cyclohexyl diisocyanate, andnaphthalene-1,5-diisocyanate.

The process of the invention directly yields the MDA complex particlesof the small particle size needed for adequate curing activity, i.e.,particles within the size limitations recited above, without the needfor any milling, grinding or other size altering steps.

The curing composition of the invention is very effective in curing, forexample, isocyanate terminated prepolymers. In general, heating themixture of prepolymer and the curative of the invention is required toeffect cure, as known in the art. In many instances, the inert carrierof the inventive curing composition will be removed, typically bydistillation under reduced pressure, prior to cure.

Surprising advantages have been found when the curing compositions ofthe invention are used to cure polyurethane prepolymer mixtures. Asstated above, the inert carrier of the invention effectively dispersesthe MDA complex throughout the prepolymer mixture, but is also readilyremoved so that it does not cause complications when the prepolymerunder goes cure. In cases where very high viscosity is encountered inpreparing the prepolymer mixture, it is possible to use additionalcarrier solvent of the inventive composition without impacting the endresults because the carrier solvent of the composition is typically, andreadily, removed. High temperatures which sometimes results fromdifficult blending processes, and the premature curing that is caused,are thus avoided.

It has also been found that physical properties of the finalpolyurethane resin are often enhanced when using the curing compositionof the invention. For example, a curing composition was prepared bymixing methylenedianiline, sodium chloride, water, surfactant andtoluene to make a wet stage intermediate. Water was removed byazeotropic distillation to make the dry stage intermediate. Isocyanatewas added, either along with additional surfactant (INV A), or withoutadditional surfactant (INV B), to react with the free MDA to yield a lowviscosity curing composition of the invention with low amounts of freeMDA. The curing composition was then mixed with a commercialMDI-terminated polycaprolactone prepolymer, the toluene removed byvacuum distillation and the resulting mixture was poured into hot moldsand cured to give plasticizer free polyurethane elastomeric samples.

The polyurethane elastomeric samples thus prepared were compared withsamples prepared from a mixture of the same prepolymer and acommercially available MDA complex curing composition comprising aphthalate ester plasticizer (˜7% by weight) as inert carrier. It wasfound that the dynamic modulus of the plasticizer free compositions INVA and INV B is about 25% higher than the standard plasticizer containingstandard composition (Std) Table 1, while maintaining a similar losstangent, Table 2.

Enhanced physical properties were also found when curing compositions ofthe invention were prepared using NaBr in place of NaCl. The aboveprocedures were repeated to prepare NaBr coupling agents, INV C wasprepared using additional surfactant while reacting free MDA with anisocyanate, INV D did not use the additional surfactant.

It is interesting to note that the addition of additional surfactantduring the isocyanate quenching of free MDA made almost no difference inthe results for INV A vs INV B, but for INV C and INV D, the NaBrcoupling agents prepared with and without additional surfactant duringthe isocyanate quenching of free MDA, INV C and INV D, did show somevariance in elastomer properties.

TABLE 1 Modulus (E+08 dyn/cm²) of INV A, B, C and D vs Std Temp ° C. StdINV A INV B INV C INV D 30 1.70 2.20 2.16 1.98 1.88 40 1.74 2.18 2.151.93 1.87 50 1.75 2.16 2.14 1.89 1.90 60 1.77 2.16 2.15 1.88 1.92 701.79 2.17 2.17 1.92 1.98 80 1.82 2.19 2.19 1.94 2.04 90 1.86 2.22 2.221.96 2.12 100 1.88 2.24 2.24 1.99 2.12 110 1.90 2.26 2.26 2.01 2.16 1201.90 2.28 2.28 2.02 2.18 130 1.90 2.29 2.29 2.03 2.20 140 1.90 2.27 2.282.03 2.22 150 1.88 2.23 2.24 2.02 2.22 160 1.85 2.18 2.19 1.97 2.21 1701.76 2.10 2.11 1.90 2.17 180 1.57 1.90 1.93 1.74 2.08

TABLE 2 Tan δ of INV A, B vs Std Temp ° C. Std INV A INV B INV C INV D30 0.039 0.047 0.045 0.057 0.057 40 0.033 0.040 0.039 0.052 0.050 500.028 0.034 0.034 0.046 0.043 60 0.025 0.031 0.031 0.040 0.038 70 0.0230.028 0.028 0.037 0.035 80 0.022 0.026 0.026 0.034 0.033 90 0.021 0.0250.025 0.032 0.030 100 0.020 0.024 0.023 0.030 0.028 110 0.020 0.0230.022 0.029 0.027 120 0.020 0.023 0.022 0.028 0.026 130 0.020 0.0230.022 0.027 0.025 140 0.022 0.024 0.023 0.027 0.024 150 0.022 0.0270.024 0.028 0.024 160 0.023 0.028 0.026 0.029 0.023 170 0.027 0.0310.027 0.031 0023 180 0.036 0.036 0.034 0.035 0.024

Other differences in physical properties were also detected betweenpolyurethanes prepared using NaCl based curing compositions and thoseusing NaBr based curing compositions. For example:

Elastomers prepared from plasticizer free (MDA)₃NaBr complexes and,e.g., MDI-terminated polycaprolactone prepolymers, have higher Trousertear and lower compression set when compared to elastomers prepared fromthe same prepolymers and either the plasticizer free (MDA)₃NaCl of theinvention or commercially obtained (MDA)₃NaCl.

The tan δ data of the (MDA)₃NaBr elastomers prepared above indicatesthat the glass transition and critical temperatures are higher than thatof the (MDA)₃NaCl elastomers.

Embodiments of the invention thus provide polyurethane compositionscomprising the small particle MDA salt complex of the invention and apolyurethane prepolymer, methods for preparing the compositions andpolymer resins and articles prepared therefrom.

The curing composition of the invention can be used with a wide varietyof polyurethane prepolymers. The polyurethane prepolymers, for example,are obtained by reacting a polyol with a polyisocyanate monomer, e.g., adiisocyanate monomer via procedures known in the art. For example, asfound in U.S. Published Patent Application No. 2003/0065124, filed Aug.2, 2001, the entirety of which is incorporated herein by reference.

Typically, the prepolymer comprises the reaction product of a polyol anda diisocyanate monomer with excess molar amounts of the diisocyanatemonomer. As such, the isocyanate groups of the diisocyanate “cap” thehydroxyl groups of the polyol resulting in an isocyanate terminatedprepolymer. The polyurethane prepolymer may comprise a plurality ofpolyols and/or isocyanates.

Exemplary polyols include polyether, polyester, polycarbonate,polycaprolactone, and/or hydrocarbon polyols. In various embodiments,the polyol may comprise one or more “high MW” polyol, e.g., one or moreof a polyether, a polyester, a polycarbonate, or a polycaprolactonediol, having a molecular weight (MW) ranging from 250 to 6000, e.g.,from 400 to 3000 or from 1000 to 2500. Low MW polyols, i.e., polyolswith an average molecular weight of less than 250, may also be used,including aliphatic glycols such as ethylene glycol, diethylene glycol,dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol,and the like.

High MW polyols include polyalkylene ether polyols having the generalformula HO(RO)_(n)H, wherein R is an alkylene radical and n is aninteger large enough that the polyether polyol has a number averagemolecular weight of at least 250. Such polyalkylene ether polyols arewell-known and can be prepared by the polymerization of cyclic etherssuch as alkylene oxides and glycols, dihydroxyethers, and the like,using methods known in the art.

High MW polyols also include reaction products of adipic acid, succinicacid, isophthalic acid and other difunctional or multifunctionalcarboxylic acids with glycols, such as ethylene glycol, 1,2-propyleneglycol, 1,4-butylene glycol and diethylene glycol, tetramethylene etherglycol, and the like. Some polyester polyols also employ caprolactoneand dimerized unsaturated fatty acids in their manufacture, e.g., apolyester polyol obtained by the addition polymerization ofe-caprolactone in the presence of an initiator.

For example, polyols useful in the preparation of theisocyanate-terminated polyurethane prepolymer of this includepolypropylene glycol (PPG); PPG diol polymer from propylene, PPG-EO diol(copolymer from propylene oxide and ethylene oxide);dihydroxypolyesters; poly(ethylene adipate) glycol (PEAG)(poly(trimethylolpropane ethylene adipate) glycol (PTEAG),poly(tetramethylene ether) glycol (PTMEG), However, many other polyolsare known in the art and may be used in the invention.

As with the polyol portion of the prepolymer, a wide variety ofpolyisocyanate monomers may be used in the preparation of theprepolymer, i.e., the poly isocyanate monomer may be any polyisocyanate, e.g., aliphatic diisocyanates or aromatic diisocyanates.Common aliphatic diisocyanates include 1,6-hexane diisocyanate (HDI),isophorone diisocyanate (IPDI), and methylene bis(p-cyclohexylisocyanate) (H12MDI), dibenzyl-4,4′-diisocyanate, isophoronediisocyanate (IPDI), 1,3 and 1,4-xylene diisocyanates, 1,3-cyclohexyldiisocyanate, 1,4-cyclohexyl diisocyanate (CHDI) and mixtures thereof.

Typical aromatic diisocyanates include diphenylmethane diisocyanate(“MDI”), optionally polymeric MDI, toluene diisocyanate (“TDI”),naphthalene diisocyanate (NDI), 3,3′-bitoluene diisocyanate (TODI),diphenyl 4,4′-diisocyanate (“DPDI”), tetramethylxylylene diisocyanate(“TMXDI”), and para-phenylene diisocyanate (PPDI),stilbene-4,4′-diisocyanate, benzophenone-4,4′-diisocyanate, and mixturesthereof.

In certain embodiments, the diisocyanate monomers are selected from MDIPPDI, MDI, TDI, HDI and C₁₂MDI, e.g., PPDI, TDI and MDI.

The prepolymer is often prepared using an excess of the polyisocyanatemonomer resulting in a prepolymer mixture containing unreacted monomer,e.g., unreacted or “free” diisocyanate. Levels of 20 wt % or more freemonomer may be encountered. In some embodiments, the level of freediisocyanate in the prepolymer mixture may be at a reduced level, e.g.,the prepolymer mixture may be a “low free” diisocyanate prepolymermixture, e.g., free diisocyanate levels of less than 10 wt %, less than5 wt %, less than 3 wt %, less than 1 wt %, or less than 0.5 wt %. As anexample, free diisocyanate in the prepolymer mixture may be removed bydistillation as is known in the art to provide prepolymer mixturescontaining from about 0.001 to about 0.5% wt % MDI, e.g., from about0.01 to about 0.3 wt %.

One embodiment relates to a composition prepared by mixing a prepolymerwith the curative composition of the invention, which compositioncontains all the elements of the inventive dispersion including thenon-polar carrier solvent with a bp of less than 160° C. Otherembodiments relate to composition prepared by mixing the curativecomposition with the prepolymer followed by removal of most or all ofthe non-polar carrier solvent with a bp of less than 160° C. to providea low solvent prepolymer mixture.

As known in the art, the MDA complex of the curing composition may beused in storage stable one pack, i.e., 1K, polyurethane compositions,which comprise an isocyanate terminated prepolymer and the MDA complexas curative. That is the curative and the prepolymer may be combinedinto a single composition which can be stored without reacting, andwhile longer storage times may be suggested with certain specificformulations, depending on temperature, storable 1K compositions aretypically stable for a day up to 6 months at temperatures of 50° C. orless, and up to a week or more, e.g., 2 weeks, one month or up to threemonths at temperatures of up to 70° C.

Because many 1K polyurethane compositions are stored for extendedperiods of time, and because at the time of the invention there waslittle to no information how the presence of the carrier solvents of theinvention would affect the storage stability of the 1K formulations, oneembodiment of the invention specifically relates to a 1K compositionprepared by mixing the curative composition with the prepolymer followedby removal, typically by distillation, of most or all of the non-polarcarrier solvent with a bp of less than 160° C. to provide a low solventprepolymer mixture.

For example, one embodiment provides a polyurethane prepolymercomposition comprising; an isocyanate terminated polyurethaneprepolymer,

-   a small particle 3:1 coordination complex of 4,4′-MDA and an alkali    metal salt, having an average diameter of e.g., from 1 to 50 μm,    often less than 20 micron etc. as above,-   less than 1 wt % of a plasticizer selected from the group consisting    of esters of polycarboxylic acids and monohydric alcohols or    phenols, esters of polyols and monocarboxylic acids, triesters of    phosphoric acid, aromatic hydrocarbons with a boiling point of over    200° C. and aliphatic hydrocarbons with a boiling point of over 200°    C., and-   less than 5 wt % of a non-polar solvent with a bp of less than 160°    C.

Generally the polyurethane prepolymer composition comprises less than0.1 wt %, or less than 0.01 wt %, of the plasticizer. Other optionalcomponents found in the inventive curing composition are generally partof the polyurethane composition

In addition to the possible impact of the solvent carrier on the storagestability of the 1K formulation, there are also flammability concerns.The carrier solvents of the present invention are typically volatilewith low flash points, e.g., toluene flashes at 4° C. Although thecarrier solvent is distilled from the 1K polyurethane prepolymercomposition, residual solvent will most likely be present. As highertemperatures are typically encountered during the curing process, e.g.,70° C. to 140° C. and sometimes higher, tests were run to determine theflash point of the 1K compositions prepared using the inventive curingcompositions. For example, IK polyurethane compositions were preparedfrom a prepolymer and a MDA/NaCl complex with known concentrations,determined by GC, of toluene and cyclohexane and subjected to standardflash point determinations.

For the toluene samples, the flash point at 5 w % toluene was 52° C.,however no flash was detected at 2% at temperatures above 140° C. and ina separate test, no flash was detected at 1% at temperatures up to 150°C.

For the cyclohexane samples, the sample containing at 2 wt % cyclohexaneflashed at room temperature, with 1% cyclohexane the sample did notflash till 149° C., and 0.5% cyclohexane did not flash at temperaturesup to 150° C.

In certain embodiments therefore, the polyurethane prepolymercomposition generally comprises 2 wt % or less, e.g., 1 wt % less or 0.5wt % or less, 0.1 wt % or less, of the non-polar solvent with a bp ofless than 160° C. For example, a polyurethane prepolymer compositiongenerally comprises less than 1 wt % cyclohexane, often between about0.05 and 0.25 wt % cyclohexane.

1K prepolymer compositions were prepared from an isocyanate cappedprepolymer, for example, a MDI-terminated polycaprolactone prepolymer,and curing compositions of the invention prepared using cyclohexane,toluene, methyl cyclohexane, and heptane as the inert carrier. Oncecured, the 1K polyurethane compositions of the invention generallyprovided polyurethane resins with greater tear strength, increasedhardness and lower compression set and rebound than polyurethanesprepared using the same MDA complex dispersed in a traditionalplasticizer carrier. For example, a mixture comprising a MDI-terminatedpolycaprolactone prepolymer and a suspension of MDA/NaCl complex incyclohexane prepared according to the invention was cured to preparetest samples and compared to test samples obtained by curing a mixtureof the same prepolymer and a suspension of MDA/NaCl complex in aphthalate ester.

MDA/NaCl Carrier Cyclohexane Phthalate Shore A Hardness 95 92 BashoreRebound 58 60 Die C Tear (lbf/in) 584 562 Compression Set (%) 23.3 24.9Split tear (lbf/in) 172 155 Trouser Tear (lbf/in) 576 468

The storage stability of the 1K formulations was also investigated.Samples were stored under nitrogen at 50° C. and 70° C. for up to fourweeks and periodically screened for increases in viscosity or prematurecure, and to determine whether the physical properties of cured polymerresin from aged formulations was equal to cured polymer resin fromnon-aged formulations.

Good results were obtained for curatives prepared in e.g., toluene,cyclohexane, methyl cyclohexane, and heptane upon storage of up to 4weeks at 50° C. Samples were of course less stable at 70° C., howeveracceptable results were also frequently obtained at that temperature.

During storage of some of the samples, it was found that better storagestability could frequently be obtained by preparing a 1K formulationwith additional isocyanate, either added to the prepolymer/curativemixture or present in the prepolymer as received. These effects appearedto be variable depending on the materials and processes used in thepreparation of the curing composition.

The low carrier solvent 1K polyurethane composition of the invention canbe conveniently prepared by mixing the curing composition of theinvention with a prepolymer, often at temperatures of from 20° C. toabout 100° C., typically at temperatures of 25° C. or higher and as highas 80° C. or lower, e.g., from 35° C. to about 75° C., until thecurative is thoroughly dispersed, e.g., from about 0.1 to about 4 hours,and then distilling off the solvent that the curative was dispersed in,in most cases under vacuum.

The above process can be run with obvious modifications using curingcompositions of the invention prepared as dispersions in other non-polarsolvents with a bp of less than 160° C., e.g., methyl cyclohexane,toluene, heptane, hexane and the like.

The polyurethane resins prepared using the curing compositions of thepresent invention can be used in the formation of any final articleknown to be prepared from polyurethanes, including a variety of film,sheet and profile applications, casters, wheels, rollers, tires, belts,sporting goods, footwear, protection equipment, medical devicesincluding surgical instruments and body parts, interior, exterior andunder the hood auto parts, power tools, hosing, tubing, pipe, tape,valves, window, door and other construction articles, seals and gaskets,inflatable rafts, fibers, fabrics, wire and cable jacketing, carpetunderlay, insulation, business equipment, electronic equipment,connectors electrical parts, containers, appliance housings, toys etc.

Plasticizer-free MDA complexes were successfully synthesized in organicsolvents such as toluene, methyl cyclohexane, heptane and cyclohexane.Conversion rate of MDA to (MDA)₃*NaCl or (MDA)₃*NaBr in the presentsolvents are comparable or higher than in DOA as demonstrated by the lowfree MDA level after wet stage. 1K polyurethane compositions prepared byblending the present curing compositions with prepolymers followed byremoval of the solvent showed very good stability when aged at 50° C.and acceptable stability at 70° C.

EXAMPLES General Process for Preparing Curing Compositions

The curing compositions are prepared, unless otherwise noted, in a threestep process:

1) Wet stage—Solid 4,4′-methylenedianiline is slowly added to a stirredmixture of non-polar solvent with a bp of 160° C. or less, a polypropoxyquaternary ammonium chloride surfactant, e.g., VARIQUAT CC42NS,abbreviated herein as “NS”, NaCl or NaBr added as a solid, NaCl or NaBradded as brine, and water, typically at 50° C., on occasion at roomtemperature. The resulting mixture is stirred until no solid MDA isvisible.2) Dry stage—The wet stage intermediate is stirred at 50° C. (typically)and vacuum is gradually applied to remove water via azeotropicdistillation until no additional water droplets are observed,co-distilled solvent is returned to the reaction mixture, e.g., asoverflow from a Dean Stark trap.3) Scavenge stage—Additional solvent and surfactant are added, including“NS” above and an ethoxylated octyl phenol surfactant e.g., TRITON 15×,abbreviated herein as “TS”, and while stirring the resulting mixture at50° C. an isocyanate is added drop wise, the following examples use4,4′-methylenebis (cyclohexylisocyanate), and the resulting mixturestirred.

The following solvents were successfully employed as the inert carrier.

Solvent Polarity Index Boiling Point (1 atm) Cyclohexane 0.2 80.7° C.Toluene 2.4 110-111° C. Methyl cyclohexane 1.2 101° C. Heptane 0.1 98°C.

Example 1 MDA/NaCl in Cyclohexane Wet Stage

To a stirred mixture of 643.3 grams of cyclohexane, 18.0 gramspolypropoxy quaternary ammonium chloride surfactant (i.e. NS), 77.7grams NaCl added as a solid, an additional 20.3 grams of NaCl in brine,and 60.9 grams of water at 50° C. was slowly added 900 grams solid MDA.MDA pellets dissolved/reacted fairly quickly and the reaction mixtureturned creamy white. The resulting mixture was stirred overnight untilno solid MDA is visible. Wet stage MDA % was 0.163.

Dry Stage

An additional 150 mL of cyclohexane was added to the reaction mixture,which was heated at 50° C. and vacuum was gradually applied. Water wasremoved via azeotropic distillation until no additional water dropletswere observed, co-distilled cyclohexane was returned to the reactionmixture as overflow from a Dean Stark trap. Water came out quicklyduring dry stage and the water and cyclohexane layers separated easily.Approximately 56 mL water was collected in the Dean-Stark apparatus,after 6-8 hrs of stripping and water content was 528 ppm; Dry stage MDA% was 0.212.

Scavenge Stage

A) To 347.60 g of the dry stage intermediate was added 43 g cyclohexane,3.56 g NS, and 9.888 g of an ethoxylated octyl phenol surfactant (i.e.,“TS”). The resulting mixture was allowed to mix well at 50° C. and 1.74g of 4,4′-methylene bis(cyclohexylisocyanate) was added drop wise. Thereaction was stirred for 3 hrs before adding 5.20 g additional NS. MDA %of the final product was 0.198.

B) To 494 g of the dry stage intermediate was added 4.9 g cyclohexane,14 g NS, and 60 g TS. The resulting mixture was allowed to mix well at50° C. and 5.75 g of 4,4′-methylene bis(cyclohexylisocyanate) was addeddrop wise. The reaction was stirred for 3 hrs before adding 5.75 gadditional NS. MDA % of the final product was 0.128.

Example 2 MDA/NaCl in Cyclohexane, MDA added in Scavenge Stage

The wet stage and dry stage procedure of example 1 was repeated. FreeMDA % of the wet stage intermediate was 0255; dry stage intermediatefree MDA % was 0.27.

Scavenge Stage

The general procedure of Example 1A) scavenge stage was repeated using432 g dry stage product except that 3.76 g MDA was added along with 5 g4,4′-methylene bis(cyclohexyl isocyanate). The final product has 0.0856%free MDA. Products remained well dispersed, upon rolling, after storage.

Example 3 MDA/NaBr in Cyclohexane Wet Stage

To a stirred mixture of 643.5 grams of cyclohexane, 12.1 grams NS, 73.3grams NaBr added as a solid, and additional 40.9 grams NaBr in brine,and 50.0 grams of water at 50° C. was slowly added 600 grams solid MDA.The resulting mixture was stirred overnight until no solid MDA isvisible. Wet stage MDA % was 0.074.

Dry Stage

The reaction mixture was heated at 50° C. and vacuum was graduallyapplied. Water was removed via azeotropic distillation, co-distilledcyclohexane was returned to the reaction mixture as overflow from a DeanStark trap. Dry stage water content was 467 ppm; Dry stage MDA % was0.033.

Scavenge Stage

A) To 370 g of the dry stage intermediate was added 60 g of cyclohexane,2.61 g NS, and 7.46 g TS. The resulting mixture was allowed to mix wellat 50° C. and 2.12 g of 4,4′-methylene bis(cyclohexylisocyanate) wasadded drop wise. The reaction was stirred for 3 hrs before adding 3.93 gadditional NS. MDA % of the final product was 0.034.

B) To 250 g of the dry stage intermediate was added 60 g of cyclohexane,1.76 g NS, and 5.04 g TS. The resulting mixture was allowed to mix wellat 50° C. and 0.63 g of 4,4′-methylene bis(cyclohexylisocyanate) wasadded drop wise. The reaction was stirred for 3 hrs before adding 2.65 gadditional NS. MDA % of the final product was 0.030.

Example 4 MDA/NaCl in Toluene

The wet stage and dry stage procedure of Example 1 was repeated usingtoluene in place of cyclohexane. The wet stage reaction was runovernight, wet stage MDA % 4.155. After dry stage water content was ˜800ppm and MDA % was 2.272.

Scavenger Stage

A) The scavenge stage of example 1A was repeated using a 1:1 ratio ofthe NCO/NH₂ (eq/eq). Final MDA % was 0.7545.

B) The scavenge stage of example 1A was repeated using a 2:1 ratio ofthe NCO/NH₂ (eq/eq). Final MDA % was 0.3939.

Example 5 MDA/NaCl in Toluene, Room Temperature Wet Stage

The wet stage and dry stage procedures of Example 4 was repeated exceptthat the wet stage was carried out at room temperature and required 40hours for completion. Free MDA level after wet stage reaction was1.474%. Water was stripped during the dry stage for ˜20 hours. watercontent after Dry stage was ˜600 ppm; Free MDA % was 1.747%. Thescavenge stage procedure of example 4B was repeated with the dry stageintermediate to yield a final product with a free MDA % of 0.7559%.

Example 6 MDA/NaCl in Methyl cyclohexane

The wet stage and dry stage procedure of Example 1 was repeated usingmethyl cyclohexane in place of cyclohexane. Wet stage reaction was runovernight. The reaction proceeded smoothly resulting in a creamy whitedispersion at the end of wet stage, Wet stage MDA % was 0.302; wet stagewater content was 34784 ppm. Water content after dry stage wasoriginally ˜800 ppm; after stripping an additional 4.5 hrs water contentwas ˜560 ppm; dry stage MDA % was 0.276.

Scavenger Stage

The scavenge stage was run on portions of the dry stage intermediateaccording to the procedure of Experiment 1 using different amounts ofisocyanate as follows: 1× represents a ratio of 1 eq:1 eq of NCO: aminecontent of the dry stage intermediate, 1.5× represents a 1.5:1 ratio, 2×represents a 2:1 ratio.

A) 1X isocyanate final MDA % 0.2307 B) 1X isocyanate final surfactantaddition final MDA % 0.0701 eliminated C) 1.5 X isocyanate final MDA %0.2031 D) 1.5 X isocyanate final 2 surfactant final MDA % 0.1083additions eliminated

Example 7 MDA/NaBr in Methyl Cyclohexane

The procedure of Example 3 (NaBr instead of NaCl, reduced solidscontent) was repeated using methyl cyclohexane in place of cyclohexane.Water content after the wet stage 40426 ppm, 1348 ppm after overnightdistillation. Free MDA level after wet stage was 0.087%, after dry stage0.095%. Scavenge stage added 0.5 wt % isocyanate. The final product has0.0191% free MDA. The final thin dispersion became thick and jelly-likeafter storing at room temperature overnight, but returned to fluid uponstirring.

Example 8 MDA/NaCl in Heptane

The procedure of Example 1 was repeated using heptane in place ofcyclohexane. Reaction mixture showed the typical creamy white textureshortly after the reaction started, however, the viscosity of themixture was higher than usual. MDA pellets disappeared after ˜26 hours.Wet stage 0.105% free MDA. Dry stage reaction was not performed due tohigh viscosity.

Example 9 MDA/NaCl in Heptane, Reduced Solids

The procedure of Example 9 was repeated a lower solid content todecrease viscosity. MDA pellets were still visible after 24 hrs. MDApellets disappeared after ˜48 hours. Wet stage free was 0.115%. Only 2-3mL water was collected in Dean-Stark despite of steady reflux during drystage reaction, however, water content in the product decreased to ˜500ppm. Scavenge reaction run according to Example 1A was carried outsuccessfully using 0.5 wt % isocyanate.

General Process for Preparing 1K Polyurethane Compositions:

The 1K polyurethane compositions are prepared in the following manner.Molten prepolymer is optionally degassed and maintained at 50° C. withagitation. The curing composition of the invention (95% stoi) as adispersion in the selected solvent is added to the reactor slowly, givensome time for the curative to be dispersed into the prepolymer.Optionally, additional isocyanate (MDI) is added. After an additional 10min to 3 hours of mixing, the pressure is gradually reduced using avacuum pump and held at a desired level to remove the dispersion solventso that less than 2% solvent remains.

In the following Examples, commercially available MDI-terminatedpolycaprolactone prepolymers were used to prepare the following 1Kpolyurethane compositions:

Prepolymer A is a MDI-terminated polycaprolactone prepolymer containing<1% free MDIPrepolymer B is a MDI-terminated polycaprolactone prepolymer containing2.4-3.0% free MDI.Compositions were cured 140° C. and post cured at 140° C. for 24 hours.

Stability of Cyclohexane-Based 1K

Samples the 1K compositions were stored in 8 oz glass jars with nitrogenblanket and then placed in dry cans. Samples were aged at 50° C. and/or70° C. The change in viscosity was measured, reported in cP, at 50° C.and/or 70° C. with spindle 27 at 10 rpm unless otherwise noted. T0represents the sample before aging.

IK Polyurethane Compositions from Curative Compositions in Cyclohexane

According to the general procedure above, prepolymer B was mixed withthe curative of Example 1A, 2, and 3A to produce the 1K compositionscontaining less from about 0.05 to about 0.5 wt % cyclohexane aftervacuum distillation. Samples were aged at 50° C. and 70° C. andviscosity measurements were taken at 50° C. and 70° C. as describedabove.

IK Composition Prepolymer Free MDI Curative Example 10 B 2.4-3.0% Ex 1A,MDA/NaCl Example 11 B 2.4-3.0% EX 2, MDA/NaCl MDA added Example 12 B2.4-3.0% Ex 3A, MDA/NaBrViscosity (cSt) of IK Polyurthene Composition Upon Aging

Aged@50° C. Aged@70° C. EX 10 vis@50 C. vis@70 C. vis@50 C. vis@70 C. T08275-8325 3075 — —  1 d 8725-8775 3225-3275 14575-14900 5425-5550  3 d9100-9175 3300-3325 15525-15775 5625-5725  7 d 9450-9700 3425-350016850-16925 6150-6200 14 d 10100-10200 3550-3600 22100-22225 7700-780030 d 11325-11550 3975-4025 Very Thick 14350Viscosity (cSt) of IK Polyurthene Composition Upon Aging

EX 11 Aged@50° C. Aged@70° C. (MDA added) vis@50 C. vis@70 C. vis@50 C.vis@70 C. T0 7925-7950 2725-2750 — —  1 d 8050-8100 2925-2950 9500-96253150-3200  3 d 8525-8550 2875-2900 9900-9975 3325-3359  7 d 8850-89002950  1150-11575 3825-3850 14 d 9650-9850 3125 14600-14625 4800-4825 30d 10150 3400 — 11900Viscosity (cSt) of IK Polyurthene Compositions Upon Aging

Ex 12 Aged@50° C. Aged@70° C. (MDA/NaBr) vis@50 C. vis@70 C. vis@50 C.vis@70 C. T0 9950-9000 3975-4000 — —  1 d 8900-9000 3300-3325 9275-95003500-3575  2 d 9100-9175 3325-3400 10325-10625 3725-3825  5 d10325-10550 3975-4025 17950-18200 6325-6450  7 d 10000-10050 3625-365062500-64000 18700-19025 14 d 11050-11225 4050-4100 Cured — 30 d15100-15275 5350-5400 Cured —IK Polyurethane Compositions from Curative Compositions in Toluene

According to the general procedure above, prepolymer A was mixed withthe curative of Example 5 and 4 to produce 1K compositions. Samples ofthe 1K compositions were cured at 140° C. and additional samples wereaged at 50° C. and 70° C. as above. Data for aged samples reported formeasurements at 50° C.

Ex 13 was prepared using the curative of Example 5 and contained about0.5 wt % toluene after vacuum distillation. The cured polymer had ahardness of 88-90 A.

Ex 14 was prepared using a 7 day old sample of the curative of Example 5diluted with additional toluene and contained about 1.3 wt % tolueneafter vacuum distillation. The cured polymer had a hardness of 89-90 A.

Ex15 was prepared by combining the prepolymer, the curative of Example4, and an additional 3 wt % MDI; and contained about 0.6 wt % tolueneafter vacuum distillation. The cured polymer had a hardness of 92-93 A.

IK Composition Prepolymer Free MDI Curative Example 13 A <1% Ex 4Example 14 A <1% Ex 5 Example 15 A ~ 3%  Ex 4Viscosity (cSt) @ 50° C. Of IK Polyurthene Compositions Upon Aging

Example13, <1% MDI EXAMPLE 15, 3% MDI aged@ 50° C. aged@70° C. aged@ 50°C. aged@70° C. T0 15,175-15,300 — 6,675-6,825 —  2 d 19,600-19,725 cured9150-9225 9575-9375  7 d 40450 — 9225-9325 13400-13700 14 d — —10600-10625 18325-18350IK Polyurethane Compositions from Curative Compositions in MethylCyclohexane

According to the general procedure above, prepolymer A or B was mixedwith the curative of Example 6B, 6C, 6D, and 7 (MDA/NaBr to produce the1K compositions containing from about 0.05 to about 0.9 wt % methylcyclohexane after vacuum distillation. Samples were aged at 50° C. and70° C. and viscosity measurements were taken at @50° C. and 70° C. asabove.

IK composition Prepolymer Free MDI Curative Example 16 A   <1% Ex 6B,MDA/NaCl Example 17 B ~ 2.5% Ex 6C, MDA/NaCl Example 18 B ~ 2.5% Ex 6D,MDA/NaCl Example 19 B ~ 2.9% Ex 7, MDA/NaBrViscosity (cSt) @ 50° C. Of IK Polyurthene Compositions Upon Aging

Ex 16 - vis@ 50° C. Ex 18 - vis@ 50° C. aged@ 50° C. aged@70° C. aged@50° C. aged@70° C. T0 10,850-10,925 — 7,775-7,800 — 2 d — — 8,100-8,200solid 3 d — 64,300-66,700 — — 5 d — — 12,400-12,500 — 7 d 18,025-18,200— — —

Viscosity (cSt) of IK Polyurthene Compositions Upon Aging

Aged@50° C. Aged@70° C. Ex 17 vis@50 C. vis@70 C. vis@50 C. vis@70 C. T09050-9125 33250 — — 3 d 11,500-11,675 3,850-3,900 18,325-183756,725-6-750

Viscosity (cSt) of IK Polyurthene Compositions Upon Aping

Ex 19 (MDA/ Aged@50° C. Aged@70° C. NaBr) vis@50 C. vis@70 C. vis@50 C.vis@70 C. T0 10050-10100 4075-4125 — —  1 d 9550-9600 3,800-3,8509,400-9,550 3,550-3,600  3 d   9975-10,000  3975-4,000 11,800-12,1254,350-4,500  7 d 10,400-10,450 4,075-4,100 solid solid 14 d11,325-11,450 4,350-4,375 — — 40 d 23,150-23,450 7,825-8,000 — —

1. A curing composition comprising: an inert liquid carrier having apolarity index of from 0 to about 3.7 and a boiling point at atmosphericpressure of 160° C. or less; and from 10 to 90 wt %, based on the totalweight of the curing composition of a 3:1 coordination complex of4,4′-methylenedianiline and an alkali metal salt formed as solidparticles having an average diameter of from 1 to 50 μm, wherein thecuring composition comprises less than 1 wt % of a plasticizer selectedfrom the group consisting of esters of polycarboxylic acids andmonohydric alcohols or phenols, esters of polyols and monocarboxylicacids, triesters of phosphoric acid, aromatic hydrocarbons with aboiling point of over 200° C. and aliphatic hydrocarbons with a boilingpoint of over 200° C.
 2. The curing composition of claim 1, wherein thealkali metal salt is selected from the group consisting of sodiumchloride, sodium bromide, sodium iodide, potassium chloride, potassiumbromide, potassium iodide, lithium chloride, lithium bromide and lithiumiodide.
 3. The curing composition of claim 2 wherein the coordinationcomplex of 4,4′-methylene dianiline and an alkali metal salt particleshave an average diameter of 20 microns or less.
 4. The curingcomposition of claim 1, wherein the inert liquid carrier has a polarityindex of from 0 to about 3.1.
 5. The curing composition of claim 1,wherein the inert liquid carrier is selected from the group consistingof C₆₋₁₀ straight or branched alkyl, C₁₋₄ straight or branched alkylsubstituted by one or more halogen C₄₋₁₂ straight or branched alkylinterrupted by oxygen, C₅₋₁₀ cycloalkyl C₅₋₇ cycloalkyl substituted byone or more C₁₋₄ straight chain alkyl, C₃₋₄ branched alkyl, halogen,C₁₋₆ straight chain alkoxy, benzene, and benzene substituted by one ormore C₁₋₄ straight chain alkyl, C₃₋₄ branched alkyl, or halogen.
 6. Aone pack urethane composition comprising an isocyanate terminatedprepolymer and a curing composition according to claim
 1. 7. A one packurethane composition obtained by mixing an isocyanate terminatedprepolymer and a curing composition according to claim 1 followed byremoving 90% or more of the inert liquid carrier having a polarity indexof from 0 to about 3.7 and a boiling point at atmospheric pressure of160° C. or less.
 8. A one pack urethane composition comprising: anisocyanate terminated prepolymer, and particles of a coordinationcomplex of 4,4′-methylenedianiline and an alkali metal salt having anaverage diameter of from 1 to 50 μm, and less than 5 wt %, e.g., 2% orless, of an organic liquid having a polarity index of from 0 to about3.0 and a boiling point at atmospheric pressure of 160° C. or less,wherein the curing composition comprises less than 1 wt % of aplasticizer selected from the group consisting of esters ofpolycarboxylic acids and monohydric alcohols or phenols, esters ofpolyols and monocarboxylic acids, triesters of phosphoric acid, aromatichydrocarbons with a boiling point of over 200° C. and aliphatichydrocarbons with a boiling point of over 200° C.
 9. The one packurethane composition according to claim 8 wherein the isocyanateterminated prepolymer is prepared from a polyisocyanate and a polyolcomprising one or more alkyl diol, alkyl triol, alkyl tetrol, polyetherpolyol, polycarbonate polyol, polyester polyol and/or polycaprolactonepolyol.
 10. The one pack urethane composition according to claim 9wherein the polyisocyanate monomer comprises one or more compoundsselected from the group consisting of 2,4-toluene diisocyanate;2,6-toluene diisocyanate: 4,4′-diisocyanatodiphenylmethane;p-phenylene-diisocyanate: diphenyl-4,4′-diisocyanate:dibenzyl-4,4′-diisocyanate; stilbene-4,4′-diisocyanate:benzophenone-4,4′-diisocyanate; 1,3- and 1,4-xylene diisocyanates;1,6-hexamethylene diisocyanate; 1,3-cyclohexyl diisocyanate;1,4-cyclohexyl diisocyanate; H(12)MDI; and isophorone diisocyanate. 11.The one pack urethane composition according to claim 10 wherein thepolyisocyanate monomer comprises one or more compounds selected from thegroup consisting of PPDI, MDI, TDI and HDI.
 12. The one pack urethanecomposition according to claim 9 wherein the isocyanate terminatedprepolymer is prepared from a polyisocyanate monomer and a polyolcomprising one or more polyester polyol or polycaprolactone polyol. 13.The one pack urethane composition according to claim 12 wherein the oneor more polyester polyol comprises a polyol ester prepared from a C₄₋₁₂linear alkyl dicarboxylic acid and a C₂₋₁₂ alkyl diol.
 14. A process forpreparing a curing composition comprising an inert liquid carrier havinga polarity index of from 0 to about 3.7 and a boiling point atatmospheric pressure of 160° C. or less, and a coordination complex of4,4′-methylenedianiline and an alkali metal salt, said processcomprising adding 4,4′-methylenedianiline to a mixture comprising i) analkali metal salt selected from the group consisting of, potassiumchloride, potassium bromide, potassium iodide, sodium chloride, sodiumbromide, sodium iodide, lithium chloride, lithium bromide, lithiumiodide; ii) one or more inert liquid carrier inert liquid carrier havinga polarity index of from 0 to about 3.7 and a boiling point atatmospheric pressure of 160° C. or less; iii) a surfactant: and iv)brine and/or water, wherein there is present at any point during theprocess less than 1.0 wt % plasticizer selected from the groupconsisting of esters of polycarboxylic acids and monohydric alcohols orphenols, esters of polyols and monocarboxylic acids, triesters ofphosphoric acid, aromatic hydrocarbons with a boiling point of over 200°C. and aliphatic hydrocarbons with a boiling point of over 200° C., andwherein the coordination complex of 4,4′-methylene dianiline and analkali metal salt obtained by the process without grinding has anaverage diameter of less than 50 microns.
 15. The process according toclaim 14 wherein the surfactant iii) comprises one or more compoundsselected from the group consisting of lecithin, polyoxypropylatedquaternary ammonium halides, and phosphated glycerides.
 16. The processof claim 14, which also comprises a distillation process to removewater.
 17. The process of 16, wherein after removal of some or all ofthe water, an isocyanate compound is added to react with some or all ofthe residual methylenedianiline.
 18. A curing composition according toclaim 1 obtained by a process comprising adding 4,4′-methylenedianilineto a mixture comprising i) an alkali metal salt selected from the groupconsisting of, potassium chloride, potassium bromide, potassium iodide,sodium chloride, sodium bromide, sodium iodide, lithium chloride,lithium bromide, lithium iodide; ii) one or more inert liquid carrierinert liquid carrier having a polarity index of from 0 to about 3.7 anda boiling point at atmospheric pressure of 160° C. or less; iii) asurfactant: and iv) brine or water, wherein there is present at anypoint during the process less than 1.0 wt % plasticizer selected fromthe group consisting of esters of polycarboxylic acids and monohydricalcohols or phenols, esters of polyols and monocarboxylic acids,triesters of phosphoric acid, aromatic hydrocarbons with a boiling pointof over 200° C. and aliphatic hydrocarbons with a boiling point of over200° C., and wherein the coordination complex of 4,4′-methylenedianiline and an alkali metal salt obtained by the process withoutgrinding has an average diameter of less than 50 microns, for example 20microns or less.
 19. A curing composition according to claim 18 whereinthe surfactant iii) comprises one or more compounds selected from thegroup consisting of lecithin, polyoxypropylated quaternary ammoniumhalides, and phosphated glycerides.
 20. The curing composition of claim18, wherein the process by which the curing composition is obtained alsocomprises a distillation process to remove water and after removal ofsome or all of the water, adding an isocyanate compound to react withsome or all of the residual methylenedianiline.
 21. The curingcomposition of claim 20, wherein the isocyanate compound added to reactwith some or all of the residual methylenedianiline intermediate isselected from the group consisting of phenyl isocyanate, p-tolylisocyanate, cyclohexyl isocyanate, butyl isocyanate,tolylene-2,4-diisocyanate, mixtures of tolylene-2,4-diisocyanate withtolylene-2,6-diisocyanate, 4,4′-methylenebis(phenyl isocyanate),2,4,4′-triisocyanato-diphenyl ether, phenylene-1,4-diisocyanate,4,4′-methylenebis(cyclohexyl isocyanate), para-phenylene diisocyanate,1,6-hexane diisocyanate, isophorone diisocyanate, 3,3′-bitoluenediisocyanate, 1,4-cyclohexyl diisocyanate, andnaphthalene-1,5-diisocyanate.